Engine room telegraph



,1 H. H. CURRY 2, 79,476

ENGINE ROOM TELEGRAPH Filed March 14, 1946 5 Sheets-Sheet l I 'STARBOARD WING CONTROL PORT WING CONTROL WHEELH OU SE CONTROL gwuam bom FIG.|

an HERMAN H. CURRY ENGiNE ROOM CONTROL Dec. 25, 195] H. H. CURRY ENGINE ROOM TELEGRAPH .5 Sheets-Sheet 2 Filed March 14, 1946 HERMAN H. CURRY FIG. 2

Dec. 25, 1951 H H. CURRY 2,579,476

ENGINE ROOM TELEGRAPH Filed March 14, 1946 3 Sheets-Sheet 3 amen vim Patented Dec. 25, 1951 UNITED STATES PATENT OFFICE.

ENGINE ROOM TELEGRAPH Herman H. Curry, United States Coast Guard Application March 14, 1946, Serial No. 654,489 11 Claims. (01. 177-337) (Granted under the act of March 3, 1883,- as amended April 30, 1928; 370 O. G. 757) This invention relates to systems for transmitting motion between two or more remote stations and particularly to an improved electrically con trolled engine room telegraph.

Heretofore, complicated and costly electrical and mechanical telemetric devices have been proposed for transmitting signals between remote stations, such as the bridge and the engine room of a vessel. This is especially true in those cases where more than one transmitting device was used on the bridge for sending signals to the engine room receiver. Usually, it is desired to have signals sent to the engine room from at least three positions on the bridge of a vessel, for ex ample, the wheelhouse, and the starboard and port wings of the bridge. plurality of bridge transmitting units were employed, either complicated mechanical linkage connected all the transmitting units to a single transmitting device self-synchronized with a receiving device in the engine room, or'if the trans-' mitting stations were electrically inter-connected, a complicated panel of transfer relays were employed for connecting the last operated transmitter unit to the engine room receiver. The mechanical linkage installation was subject to freezing, added friction to the system an; was difficult to install and maintain in satisfactory operating condition. The electrical installation utilizing transfer relays was costly to install, was subject to electrical failure and objectionable because the last transmitter to be operated showed the true indication while the remaining transmitters were unaffected thereby and the different control positions indicated thereon led to confusion.

An important object of this invention is to provide an improved motion transmission system especially adapted for signaling control movements between a plurality of transmitting stations and one or more receiving stations such that all stations show the last signal transmitted. Another object of the invention is to provide an electrical transmission system operatively incorporting all the transmitters and receivers into a self-synchronizing electrical system which is automatically locked in any one of the control positions and only released from this condition upon movement of one of the transmitters toward another control position. Another object of this invention is to provide in such a self-syn chronizing system an improved sense of touch or feel for facilitating the control thereof. A further object of this invention is to provide novel warning and recording devices for indicating de- In the past when such lays or errors in transmission and reception of: signals. More specifically, this invention as applied toengine room telegraph provides a novel controlling mechanism which releasably holds all the transmitting and receiving devices in any control position selected and which is operable to release-- the system for operation when any one transmitting device is moved toward another control position. This is accomplished in the illustrated embodiment of the invention herein by the provision of one or more novel holding devices in the form of a toothed or star wheel having a roller detent yieldingly pressed into engagement therewith and an electrical device responsive to current flow in the self-synchronizing circuit for re-' tracting the detent from engagement with the star wheel. A novel feature of the invention is' the corresponding relation of the star wheel holding means to the various control positions of the system such that when all the operating parts of the system have followed up the transmitting device, the re-engagement of the roller detent with the star wheel automatically centers all the transmitting and receiving devices to the mid-- point of the control position selected. The requirement that a transmitting device be first moved toward another position before the detent' holding means releases the system provides a re-' sistance in the system which the operator must overcome. This requires little manual effort but the resistance encountered improves the feel of the system to the operators control. Furthermore, upon synchronization of all the transmit-' ting and receiving devices the operator can feel the system seeking the center of the nearest scale position.

The engine room telegraph of this invention incorporates a repeat-back self-synchronizing system whereby the engine room answers the sig-' nal from the bridge and indicates to the bridge the control movement exercised over the enginel Preferably the repcat-back system is similar to the transmission system from the bridge and in cludes all the stations on the bridge. Each station, whether on the bridge or in the engine room, has a motion transmitting device and a motion receiving device preferably arranged side by side in one unit. Each station unit has a pointer and scale for indicating the control positions of the bridge control system and a pointer and scale for indicating the control positions of the repeat-- back system. The motion transmitting device of each station unit is provided with a control handle for moving the system in which it is associated. Since both systems are self-synchronizing, the movement of any control handle, whether in the control system from the bridge units to the engine room or in the repeat-back system from the engine room unit to the bridge units, is followed by movement of all transmitting and receiving devices in the system. The novel detent holding means elastically restrains both systems in their respective control positions except when an operator intentionally makes a change in the control position. I

In order to warn personnel of any delay or error in acknowledging the transmission and receipt of signals, novel alarm devices are provided. An important object of this invention is to provide warning devices electrically associated with the bridge and repeat-back systems which sound an alarm or otherwise indicate a failure of either system to synchronize after a short delay, and which further sounds an alarm or otherwise indicates a warning when the acknowledgement or answer of the repeat-back system does not agree with the bridge control system.

A further object of the invention is to provide a novel recording device for graphically indicating the control movements transmitted from the bridge and acknowledged by the engine room. It is intended that this recording device be in operation at all times. Of special significance is the provision of special means for varying the speed of the graphic recorder. In normal operation, the speed is relatively slow, but a novel provision automatically increases the speed of the recorder when errors in transmission and acknowledgement occur resulting in a graphic amplification which serves as a clearly understandable record of the event. A further novel feature is the provision of a manual control for increasing the speed of the recorder for use at times when it is expected that many signals will be transmitted to the engine, such as when docking or undocking a vessel.

In the drawings, Fig. 1 is a diagrammatic view of a preferred form of the invention in which the several parts thereof are shown in a position registering Stop. Fig. 2 is a diagrammatic engagement with the star wheel.

view of a modified form of the invention wherein recording means are applied to the engine room telegraph system, such means shown registering an error on the part of the engine room pperator in operating the repeat-back signal device. Fig. 3 shows a modification.

Referring more particularly to Fig. 1, the system comprises a plurality of transmitting stations which may be located on the bridge or deck of a ship, the operation of any one of which will produce a corresponding operation of the receiving station which may be located in a remote place, such as a ships engine room. The

deck indicator or transmitter l I is adapted to be mounted on the port wing of the bridge, the deck transmitter l2 in the wheelhouse and the deck transmitter l3 on the starboard wing. The engine room receiver [4 is operated by these deck transmitters.

The transmitters H, l2 and '13 are identical and each thereof comprises a shaft 15, suitably journaled for rotation, upon which are aflixed the three phase rotor windings l8 of a selfsynchronous machine or motor IT. A pointer I8 is carried at one end of the shaft and operates around the face of the dial !9 which bears suitable indicia. thereon. A controller or handwheel 20 is affixed to the end of the shaft to permit rotation thereof to any desired position. To

releasably and yieldingly retain the shaft in adjusted position a star wheel 2| is afiixed to the shaft. This star wheel has seven notches which correspond to the seven positions usually used in a, ships engine room telegraph and correspond to the signal "Stop and three speeds ahead and three astern. The wheel is essentially an eight pointed star and the portion thereof which is unused is bridged as at 22 so that the detent, subsequently described, will automatically force the Wheel into the positions adjacent this particular bridged section should the shaft be rotated too far. A roller detent 23 is mounted adjacent this star wheel and rides over the edge thereof. This detent is carried by an arm 24 connected to the core of a solenoid 25 which when energized serves to withdraw the detent from A lever 26 has one end engagingthe axle of the star wheel and the other end thereof resting on a fixed pivot 27. A spring 28 attached to the lever serves to hold the detent into engagement with the star wheel. It will be seen that the detent will force the star wheel into a definite angular position and will serve to positively position the pointer 18 on the dial. This is particularly important as the synchronizing torque in systems of the kind here used decreases with the decrease in the angle of displacement so that at small angles the torque is insufiicient to produce exact synchronism of the transmitter and receiver. This may lead to a variation in the receiver pointer which would cause confusion in the engine room. With the star wheel, however, the detent serves positively to position the transmitter and receiver in the same angular position once movement of the wheel permits the detent to appear over the appropriate notch. The shaft may be turned by hand against the restraining influence of the detent, but the electrical machine affixed to the shaft may not necessarily provide enough torque to rotate the shaft a ainst the detent. The end of the shaft [5 opposite to that carrying the hand wheel 20 carries an annular commutator 29 lying in a plane nor al to the shaft and supported concentrically about the axis of the shaft by a radial member 39. The commutator 25' has a section thereof removed for a purpose subse uently described. Operatively associated with the rotor winding l6 of the machine 51 is a single phase stator winding 3|.

Deck transmitters l2 and is are identical in structure with deck transmitter -H and no fur-- ther description thereof is deemed necessary. Like parts bear similar reference numerals.

The engine room receiver I4 is similar to the transmitters described above and comprises a shaft 32 journaled for rotation, to which is affixed a rotor winding 33 of a self-synchronous machine 34, a star wheel 35 of the same configuration as star wheel 2!, and acommutator 36 positioned in the same manner as commutator; 29. A pointer 31 is provided, but no hand wheel,

35 to releasably hold the shaft in adjusted posi tion. A spring 4| biasing the pivoted lever 42'; attached to the detent, holds the detent into en=-" The detent 4G is car-- ried by the arm 43 which is connected to the" gagement with the wheel.

This same indicia apcore of solenoid .44 -for movement into and 4 outof engagement with the wheel against the spring bias when energized.

The stator windings 3t of the transmitters 1 I, I2 and I3 are all connected in parallel and are supplied with power from terminals '45 adapted to be coupled to a suitable sourceof electrical energy, say 110 volt, 60 cycle, alternating-current. This energizing circuit may be traced "through conductors 46 and. The stator winding 39 of the receiver is similarly energized. The rotor windings I6 of the-transmitters are connected in parallel by means of conductors 48 and 49.

The solenoids 25 of the transmitters H and 13 are series connected for operation in unison and are'connected to the line by conductors H6, 63, 41 and 46. The'energization of this solenoid circuit is controlled by switch I90 operated by relay IUI. This relay comprises cores I92 operating in coils I63 inthe conductors! of the circuiticonnecting the rotor windings id of thedeck transmitters H, l2 and i 3 with the rotor winding 33 of the engine room receiver 14.

Solenoid 25 of the transmitter l2 and solenoid 44 of the receiver are also connected in series for joint operation and are coupled to the line by conductors 62 and 46. A switch I94 in this solenoid circuit is operated by relay I95 comprising cores I96 operating in coils I 91 in the conductors connecting rotor windings i and 33. It will be seen that the three solenoids 25 and solenoid 45 operate in unison and simultaneously lock or unlock the detents into or out of engagement with the star wheels.

When the windings of a self-synchronous system such as that here used are properly phased, out, the rotors will remain stationary in the same angular relation-to their respective stators. The voltages in the connecting windings are then equal and opposite and no current flows therebetween. However, if the rotor of one transmitter is displaced in space phase, a resultant voltage becomes available for circulating a current through the connecting windings which will produce a torquein'the receiver tending to turn the rotor thereof to a position corresponding to the new position of the generator rotor, the'two rotors tending to move in synchronism. The magnitude of the current flowing between the transmitter rotor and the receiver rotor is a function of the angular displacement therebetween. It is this current that is'utilized in controlling the operation of thesolenoids 25 and 44 which operate the detents 2'3 and 4%, respectively.

The above description relates to the transmit ting system from bridge to engine room. The repeat-back system which will now be describedis merely the reverse of this transmittin system and comprises an engine room indicator or transmitter and a plurality of deck indicators or receivers by which the engine .room operator may repeat the signal received from the bridge back thereto.

The engine room repeat-back transmitter 64 comprises a shaft 65, axially aligned with shaft 32 and spaced a small distance, which carries a pointer 66 adapted to operate over the fixed dial 6'] and may be turned by means of the controller or hand Wheel-58. The self synchronous machine 69 has its rotor ll] afiixed to the shaft 55. A star wheel H of the same configuration as those previously described is fastened to the shaft and is engaged by a roller detent 12 engaging the teeth thereof and held thereagainst by a spring 13 acting through the pivoted lever 14 bearing'upon the detent. The'detent 12 is connected to the moveable core of solenoid 15 for movement into and out of engagement with the wheel H. A single phase primary of the machine 59 is operatively associated with the rotor winding 10. The end of the shaft opposite-that carrying the wheel H has a brush 15 extending therefrom and spaced radially thereof. The axial spacing of shafts 3'2 and 65 of the engine room receiver 14 and transmitter 64 is such that brush l6 wipes commutator 36 except when the brush is opposite the gap in the commutator.

The repeat-back receiving stations 86, 81 and 88 which are shown in association with the deck transmitting stations, are identical in construction and each thereof comprises a repeat-back receiver having a shaft '11 journaled for rotation one end of which carries a pointer 18 adapted to operate over the face of the fixed dial 19. No hand wheel is, of course, provided for any of these receivers. The shaft Tl carries the three phase rotor 39 of the self-synchronousmotor 99-and a star wheel 89 whose teeth engage the roller detent 8| held into engagement therewith by a spring biased lever 82. The detent BI is coupled to the core of a solenoid 83 by an arm 94 for movement into and out of engagement with the star Wheel 99 when the solenoid is energized. The shaft TI is axially aligned with shaft [5 of transmitter l2 and spaced a short distance therefrom. The end of shaft 11 carries an offset brush 85 adapted to wipe the commutator 29 of transmitter 12 except when the brush is opposite the gap in the commutator. Each motor 99 has a single phase stator winding 9|.

The stator windings a! of the deck receiving stations 89 and 38 are connected to a source of power by conductors 5i, 69 and 5! while that of receiver 81 is connected via conductors 92, 69 and 5!. The rotor windings 89 of the deck receivers are connected in parallel by conductors 93 and 94 and are connected to the rotor windings 19 or the engine room repeat-back transmitter 64.

Solenoids 83 of the deck receivers 86 and 88 are series connected and coupled to the line by conductors Ill, 55, El, 69 and iii. A switch 95 in the solenoid circuit is operated by relay 96 comprising cores J operating in coils 99 in the conductors 93 connecting the windings 89 of the deck receiver self-synchronous motors to the windings m or the engine room transmitter ma chine 69.

Solenoid 83 of the deck receiver 91 is connected in series witht-he solenoid 15 of the engine room transmitters 94 and are supplied with power by conductors 59, 59 and 9!. A switch no in this solenoid circuit is controlled by relay HI comprising cores operating in coils in the conductors connecting the rotor windings l9 and 89. It will be seen that the three solenoids 83 and solenoid l5 operate in unison, .as the same current energizes the relays and III for joint operation, so that the shafts of the deck receivers and engine room transmitter may rotate without the restraining effectof the detents operating on the star wheels.

Each of the deck stations has an electric bell H2 connected in series to a time delay device H3 of conventional type. This device may be set for any selected period of time, six seconds for example. The bell and time delay device are connected to the line through the brush 85 and commutator 29 by suitable lead wires. These wires have been shown connected directly to the angers:

but any suitable connection such as slip rings and contacts may be used. It will be seen that when the shafts l7 and I are angularly positioned so that the brush 85 is opposite the gap in the commutator the alarm will not be energized. But if the shaftsare angularly displaced the brush 85 will contact the commutator to complete the alarm circuit and cause the bell to rin after a predetermined time interval.

The engine room receiver and repeat-back transmitter are similarly provided with an electric bell HA and a time delay device H5 connected thereto. These two devices are connected to the line across the brush it and commutator 36 so that as lon as the shafts 65 and 32 are angularly disposed in a position to place the brush It in the gap in the commutator 36, the alarm will not be sounded. However, any angular displacement of one shaft with respect to the other will energize the alarm circuit.

The operation of the device is as follows: In

its initial setting, assumed to correspond to stop on the dial, all of the equipment is dis-' posed as indicated in Fig. 1. That is to say, all indicators point to stop on the dials, the roller detents all bear on the star wheel to hold the pointers in position and the brushes are positioned adjacent the gap in the commutators. When it is desired to transmit a signal to the engine room, any deck transmitter may be operated. For example, assume that the wheelhouse wing control is used to transmit the ahead signal to the engine room. The controller or hand wheel 28 is turned to rotate the shaft i5 in a counter-clockwise direction against the restraining effect of the detent 23 operating on star wheel 2!. The operator thus has a very definite feel that the system is properly locked in position. This turning also causes commutator 29 to contact the brush 85, completing the alarm circuit, and also displaces the rotor 16 of the self-synchronous motor i! with respect to the rotor 33 of the receiver I4. displacement causes a current to flow in the con ductors I98 connecting the rotor windings which energizes relay I55 to close switch Hi4 thus energizing the solenoids 25 and 44 of the wheelhouse control to withdraw the detents 23 and 40 from their respective starwheels, making the shafts free to rotate. If the engine room receiver fails to rotate to a position corresponding to that of the wheelhouse transmitter, the alarm H2 will sound after a six second delay. If the shaft 52 assumes the same angular position in which shaft l5 of the wheelhouse transmitter was placed, the pointer 37 will turn to ahead on the dial 38. It should be noted that movement of the shaft 32 has placed commutator 36 in contact with brush it to complete the circuit for the alarm 1 i l. If the engineer does not respond within one econd, this alarm will sound. The engineer, obser'vingthis message, then grasps controller 58 of the engine room transmitter 64 and turns the pointer 66 to ahead. The rotation of shaft 55 will cause the brush 16 to disengage the commutator 35, assumin a position adjacent the gap therein, thus breaking the alarm circuit. This angular movement of the transmitter '64 is made against the restraining influence of the detent l2 engaging the star wheel ll. It also pro-'- duces' anangular displacement with respect to the'deck receiver 8? and the current inthe conductors connectin the rotors 89 and 10 actuates the relay' Hlto close switch III] to energize the This angular solenoids Brand 15, withdrawing" the dete'nts 8i and'lz from their respective star wheels, thus permitting the motor 90 to rotate shaft 11 to move the brush to the gap in the commutator i 29 to deenergize the wheel-house alarm circuit.

If the engineer does not perform the repeat-back operation within six seconds the deck alarm H2 will sound.

When the relay H I is energized to permit unlocking of the shafts ll of receiver 87 and shaft 65, the relay 96 is also energized to close the solenoid circuit of deck receivers 86 and 88 thus unlocking their respective shafts to permit the pointers 18 to register the same readin as that of receiver 81.

The operation of the system from either of the wing control stations is identical with that set forth above in connection with the wheelhouse control.

Referring more particularly to Figure 2, I have shown a recording system combined with the transmitting system of the general type shown in Fig. l, but somewhat simplified for a readier comprehension thereof.

Deck transmitters H8, H9 and lZt comprise self-synchronous electrical machines, each having primary windings i2! connected to a source of alternatin current by conductors I22. The three phase rotor windings 523 are connected in parallel. Deck transmitter i2! has a'shaft I24 to which is aifixed a pointer I25- which operates over dial 126 bearing suitable indicia. The several ahead and astern speeds, corresponding to slow, one-half and full speed, have not been indicated in the interest of clarity. The pointer, however, is turned to indicate half speed ahead. The shafts, dials and pointers have not been illustrated for the other transmitters.

The engine room receiver l2? comprises a selfsynchronous alternating current machine having a single phase stator winding l28 and a three phase rotor winding l29 aflixed to the shaft I30. A pointer i3! is carried by one end of the shaft and operates over dial i32 upon which suitable indicia (not shown) is inscribed. The rotor windings I29 of the receiver are connected to the rotor windings 423 by conductors I33 to per mit synchronous operations of the transmitters and receiver in a manner well known in the art.

The shaft E30 has a star wheel I34 afiixed thereto which is engaged by a roller detent I35 held into engagement therewith by a spring biased lever I38. The star wheel is fundamentally an eight point star having two points bridged as at l36 to provide seven recesses which correspond to the seven speeds, viz., stop, three speeds astern and three ahead. When the detent I35 rests between the teeth the wheel is positively positioned and holds the pointer l 35 in a definite position on the dial 32. A solenoid i3! is operatively connected to the detent for removing the detent from engagement with the star wheel. The solenoid is connected to'the source of powerby conductors I39, one of which contain a switch" M9 in series therewith. A relay Mi comprising coils M2 in the conductors I33 and cores M3 serves to operate switch llii to complete the circuit to solenoid l3! to unlock the shaft Q35 of the receiver for rotation to permit it to assume an angular position corresponding to that of the transmitter whereupon switch Mil opens and the detent again engages the star wheel. An alarm 'iM is inserted in the solenoid circuit for" sounding in the engine room when a signal is transmitted. 1

The other end of the shaft I36 carries a commutator I45 supported thereon by a radial arm I46. The communtator is annular in form and mounted in a plane concentric with and normal to the axis of the shaft. The shaft also carries a bevel gear I41 meshing with a second bevel gear I48 attached to one end of shaft I49 rotatably journaled in bracket I56.

The repeat-back system comprises a engine-v room transmitter I! having a single phase stator Winding I52 and a three phase rotor winding I 58 affixed to shaft I54 journaled for rotation and axially aligned with and spaced from shaft I38. One end of the shaft carries a controller or hand wheel I55 and a pointer I58 operating over a fixed dial I5! carrying suitable indicia. The other end of the shaft carries a brush I58 axially displaced from the shaft and wiping the communtator I45, except when the brush is opposite the gap therein, to complete a control circuit described below. The shaft i54 also has a bevel gear i553 afiixed thereto which engages a bevel gear I68 affixed to the end of a shaft I6I rotatably journaied in bracket I522. The rotor winding I 58 is connected to the parallel connected three phase rotor windings I'I8 of deck receivers H9, I86 and i8l by conductors I83. The single phase primary windings I82 are connected to a source of single phase power. These receivers may be supplied with pointers and dials as shown in Fig. 1.

The shafts I46 and I6I have radial arms I63 and I64, respectively, the ends of which carry styluses I65 and I66. The recording. device upon which the stylus operates comprises a pair of drums I67 and I68 mounted on a shaft I69 driven by an electric motor I16 through a worm and wheel drive Ill. The motor is connected to the line by conductor H2, A resistance H3 in this line may be cut into or out of the motor circuit to change the speed thereof by switch I14 which may be moved to contact one end of the resistance or one end of a conductor I75 paralleling said resistance. The switch I14 is operated by. a solenoid I86. Ths solenoid circuit includes the brush I53 and commutator I 45, conductors III connecting the said elements to the line in series with the solenoid I16. When the brush I58 engages the commutator I45 the solenoid I76 is energized to operate the switch I14 to bypass the resistance I 73 and thereby increase the speed of the motor I18 to rotate the drums I68 and I69 at a greater speed. The switch I14 may also be manually operated by means of a knob I95 attached thereto.

Paper tapes I84 and I85 pass over drums I68 and I 88, respectively and receive the marks made by the stylus. The paper may be calibrated as shown, having a centrally disposed line I86 indicating stop and lines I81, I88 and I89 corresponding to slow, one half and full speed ahead, respectively, and line I68, I9I and I92 indicatin slow, one half and full speed astern.

Arms I63 and I84 move the stylus I65 and I66 over these tapes in a direction and to a degree corresponding to the movement of the receivershaft I38 and transmitter shaft I54 by reason of the beveled gears coupling the shafts to their respective stylus arms. The trace I93 on tape I84 is made by stylus I65 and the trace I94 on tape I85 by stylus I66.

While a variable speed motor has been shown;

it is obvious that any suitable speed varying means may be used in lieu thereof, such as a variable speed transmission in which case the 10 solenoid. I78 would operate the gearshifting means.

The operationof the-device is as follows. With the decktransmitter set for. stop the shaft I36 of the. receiver i2? will be in a corresponding position. If the transmitter I51 is also set for stop, the brush I58 willbe adjacent the gap in the commutator I thus opening the circuit to solenoid. I538. This will keep the switch in a positionto cutin the resistance Ill-3 and the motor willoperate at slow speed to avoid excessive use oftape. The bevel gears will turn their respect tive stylus tothe lines Iiiiion the tapes indicating thatboth receiver I23, and transmitter I5I are in agreement.

However, if thedeck. transmitter I18 is turned to half-speed ahead .as shown in Fig. 2, the current flowing conductors I33 Will operate relay Isl to close switch I48, energizin solenoid I3] t remove detent I35; from the star wheel where upon. the receiver assumesthe same pcsitionas the deck transmitter as shown by pointer I31v of, the receiver. Relay I41 willthen open switch L4]! to permit the detent to hold the shaft I36 in post-.- tion. Turning of. the shaft I38 also rotatedcommutator I45 counterclockwise into engagement with the brush 1158 thus completing the circuit tothe motor control solenoid I76 .to speed up the motor illil byeutting out resistance I73. Rotation'. of the shaft. 1:38 also rotated shaft I49. through bevel gears I47 and 1.48 a corresponding amount so that the stylus. I55 moved from the line I88 on. tape I88. to. line I88 registering a. .deck signal of one half; speed ahead.

For purposesor illustration, Fig. 2 has been drawn to illustrate the application of an erronee. ousrepeat back signal. The operator has. turned the transmitter pointer I56 to half speed astern. This movement of shaft I54 does not disengage the brush 153' from the commutator I135, the motor 118 continuing to run at high speed. Rota tion of the shaft I56 hasalso rotated shaft I6I through bevel gears i519 and .Ififlto turn the arm I64. to position thestylus I661 on the tape I85 to register thereon one half speed astern as shown bythe trace I94. .A. record has thus been made showing the signal received as well as the one repeated, back.

The operator may turn the pointer I56. of transmitter .I.5I through to one half speed ahead whereupon brush I58 will betopposite the gap in. the commutator, thus breaking the circuit to the motor control solenoid I16 and slowing down the motor I76. This movement of shaft -I 54 will; also cause .stylus I66 to be moved to register acorresponding impression on the tape I85.

Having provided means for recording the signals :between the bridge and engine room, it is desirable also to indicate on the tape other factors relating thereto, such as time, propeller speed, propeller revolutions, position of the prime moverthrottle or control lever, etc. In Fig. 2 I have shown a printing clock I96 for recording the time on the tape I85 when the engine room receiver and transmitter are :not in agreement. The printing clock is of a type-well known in the art and no further description thereof is deemed necessary other than to state that it has a printing arm carrying hour and minute hands and the date whose imprint is made on the tape at predetermined intervals when its operating solenoid (not shown) is connected to a suitable source of power. The printing arm of the clock I96 overhangs the edge of the tape I85 adjacent the end of drum I 91. The means for forcing the printing'Larin intoengagement with the tape is con-. nected in series with the brush I58, commutator I45 and the solenoid I16 so that printing of the time is only effected when the engine room receiver I2'I is angularly displaced with respect to the engine room transmitter NH. The marks made by the printing clock has been shown at I91 in Fig. 2. From this record, the time the signals wererecorded on the tapes may be found. While only one printing clock has been shown it is of course obvious that another similar clock could be-used in connection with tape I84 for the same purpose. It is also obvious that the clock could be made to print the time whenever a certain amount of tape had passed over the drum. This could be' effected by having projections on the tape at fixed distances which would operate a switch to energize the clock to record the time. It is also obvious that other recording instruments could be substituted for, or used with the printing clock shown in Fig. 2 and the same energizing circuitcould be used for operating such instruments in the same mannerin which the clock is energized.

- -In Figs. 1 and 2, thesolenoids which retract the detents from the star wheels are connected tothe line by switches operated by relays controlled by current fiowing in the conductors connecting the secondary windings. In Fig. 3 Ihave illustrated a system which uses a switch operated by movement of the transmitter detent for con trolling the solenoid circuit. -..,The transmitter I98 comprises a shaft I99 upon which is affixed a three phase rotor winding 200, a star wheel I similar to those previously described, an indicator 202 and a controller in the form of. a hand wheel.203. The bridged portion between one pair of teeth shown on the star wheels in Figs. 1 and 2 has been omitted in star wheel 20I to permit the ready disclosure of the roller.2l0. It is of course obvious that this roller could be mounted next to the roller detent 205, in which case the star wheels previously described could be used. Asingle phase primarywinding 2041s associated with the rotor winding. A roller detent 205 is mounted on the end of arod 206 carried by the coreof a solenoid 201. The detent is yieldingly held into engagement with the teeth of thestar wheel by a .pivotedlever 208 one end of whichengages the axle of the detent. A spring 20.9 holds the .detent against thestar wheel, .positively positioning the transmitter in a predetere. mined position. A second roller 2I0is mounted to ride upon the teeth of .the star wheel 20I and is yieldingly held into engagement therewith by a pivoted lever 2 II and a spring 2.!2. A rod 2I3 afiixed to the roller 2 I0 has its free end attached to the movable member of switch 2I4, in the linev I The receiver 2H5 comprises a shaft 2I'I carrying an indicator 2I8, a rotor winding 2I9 and a star wheel 220. A roller detent 22I is yieldingly held into engagement with the star wheel bya pivoted lever 222 biased by a spring..223. The detent is fastened to the core of a solenoid 224 for retraction from engagement with. the. star wheel when the solenoid is energized. Stator winding 225 is operatively associated with the rotor winding 2I9. Other features of the transmitter and receiver have not been illustrated in the in terest of simplification.

The transmitter and receiver stator windings are connected to a source of single phase alternating current by conductors 226 and the rotor leggings 9 h q g h ne ar onn t d by 12 conductors 227. The conductor 2J5 puts the switch .in series with the parallel connected solenoids 20? and 224 across the line.

The operation of the system is as follows. Rotation of transmitter shaft I99 by means of hand wheel 203 will force the roller detent 205 from between the teeth of the star wheel 20! against the tension of spring 209. At the same time roller 2I0 is similarly forced to ride upon the adjacent tooth moving the rod H3 in a vertical direction against the tension of spring 2I2 to close switch 2H1. This serves to energize solenoids 207 and 224 to retract roller detents 205 and 22I from the star wheels 20! and .220 leaving the receiver shaft free to align itself angularly with the transmitter shaft under the influence of the synchronizing torque generated by current flowing in conductors 22?. The switch 2M is designed to close before the roller 2 Ii! rides over the point of the tooth, preferably when the shaft wi l has been rotated about 10 in either direction. When the roller 2H: rides over the point of the adjacent tooth it will assume a position between that and the next tooth and will open the switch 2H5 to deenergize the solenoids 287 and 22d whereupon the springs 289 and 223 will force the detents 205 and 22I into engagement with their respective star wheels to yieldingly hold said shafts against rotation.

While but one receiver and one transmitter have been shown in Fig. 3 it is to be understood that the control system for the solenoids could be substituted for that shown in Figs. 1 and 2. Where there is a plurality of transmitters, it would only be necessary to connect the switches for each transmitter, corresponding to switch 214 in Fig. 3, in parallel and these in series with the parallel connected solenoids as shown in Fig. 3 so that the closing of any switch by movement of a transmitter shaft would close the circuit for all the solenoids to permit all of the devices to synchronize simultaneously.

While I have described the preferred form of my invention I do not wish to limit myself to the precise details as shown but wish to avail myself of such variations and modifications as may come within the scope of the appended claims.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

I claim:

1. In an electric motion transmitting system,

i a transmitting station and a receiving station remote from each other, a self-synchronous motor in each station electrically linked together by a self-synchronizing circuit for selfsynchronous operation, a controller for moving the motor in said transmitting station, means movable with said controller for indicating a plurality of control positions, means releasably holding both of said motors in any one of said plurality of positions, and means responsive to increase in current in said self-synchronizing circuit connecting said motors as. a result of moving the transmitting motor by said controller forreleasing said holding means.

2. In an electric motion-transmission system, a transmitting station and a remote receiving station each having a self-synchronous motor therein, a circuit electrically linking the motors in said transmitting andreceiving stations together for self-synchronous operation, means releasably holdinggone .of said. motors in any one of a plurality of positions, said means being in the form of a star wheel having a roller detent yieldingly pressed into engagement therewith, the teeth of said star Wheel terminating in relatively sharp points, and a solenoid electrically connected into said self-synchronizing circuit and operable upon increase in current therein to Withdraw said roller detent from engagement with the star Wheel sufiiciently to allow operation of the system.

3. In an electrical motiontransmitting system, a transmitting station and a remote receiving station each having a self-synchronizing motor therein, a circuit electrically linking the motors in said transmitting-and receiving stations for self-synchronous operation, a controller for mow ing the motor in said transmitting station, means movable with said controller for indicating a plurality of control positions, means releasabiy holding one of said motors in any one of said plurality of control positions, said last means comprising a star wheel operatively connected to one of said motors having each tooth thereof corresponding with one of said control positions and a roller yieldingly pressed into engagement with the teeth of the star wheel, a solenoid adapted upon energization to retract said roller detent from the teeth of the star wheel suificient to free the system for operation, and a circuit operatively connecting said solenoid into the self-synchronizing circuit between said motors.

4. In an electrical motion transmission system, a transmitting station having a self-synchronizing motor, a controller for moving said motor, and a pointer movable with said controller relative to a dial divided into sectors indicating a plurality of control positions to which said motor may be moved, a receiving station having a selfsynchronizing motor therein electrically connected to the motor in said transmitting station for self-synchronizing operation therewith, a star wheel fixed to one of said motors and movable therewith, the teeth on said star wheel corresponding in number to the number of said control positions and arranged so that the roots of the teeth assume the mid-points of the control positions to which they correspond, a detent carrying a roller adapted to enter the teeth of the star wheel to releasably hold the synchronized motors at the mid-point of any one oi said control positions, means yieldingly urging said detent roller into engagement with the teeth of said star wheel, a solenoid for retracting said roller detent sufficient to free the star wheel and the system for synchronized operation, and a circuit for the solenoid oper tively connected into the synchronizing circuit between said motors and responsive to the increase in current therein as a result of moving said transmitting motor to retract said roller detent.

5. An engine room telegraph system comprising in combination, a deck indicator unit and an engine room indicator unit each having a motion transmitting self-synchronous motor and a motion receiving self-synchronous motor and means for indicating the respective positions of the motors, electric circuit means connecting the motion transmitting motor of each unit with the motion receiving motor of the other unit for self-synchronous operation, an alarm device, an electric circuit for operating said alarm device normally open but adapted to be closed when the motors in one or both of said units are ing in relatively sharp points, a knob connected to the star wheel of the transmitter for manually turning the transmitter star wheel, means operable upon manually turning any one of said star wheels and forcing its associated detent from between said teeth for retracting all of said detents from engagement with said star wheels to permit said transmitter and receiver to assume the same angular position, said lastimeans being operable upon approximate realignment of said star wheel to allow said detent tov return against and exactly realign said wheels in one of said plurality of positions.

7. An engine room telegraph comprising a plurality of self-synchronous transmitters connected in parallel and a self -synchronous receiver, means connecting said transmitters and said receiver for self-synchronous operation, means releasably holding each of said transmitters and receiver in any one of a plurality of positions, said holding means comprising a star wheel having relatively sharp teeth thereon and a roller detent yieldingly engaging said teeth, electrical means for simultaneously retracting all of said detents from engagement with said star wheels, a circuit for energizing said electrical means, a knob connected to the star wheel of the transmitter for manually turning the transmitter star wheel, and means operable upon manually turn ing any one of said star Wheels and forcing its said detent from between said teeth for energizing said circuit to retract said detents, permitting said transmitters and receivers to assume the same angular position.

8. In an electrical motion transmitting systerm, a transmitting station and a receiving station remote from each other, a seli-synchronous motor in each station electrically linked together by a self-synchronous circuit for selfsynchronous operation, a controller for moving the motor in said transmitting station, means movable with said controller for indicating a plurality of control positions, a cam fixed to rotate with the self-synchronous motor at the receiving station, said cam having a plurality of closely spaced depressions, each depression corresponding to one of said control positions, a follower means yieldingly pressed against said cam, said cam and said follower being so constructed that said follower will cause said cam when yieldingly pressed thereagainst to move to the nearest control position, and means responsive to a change in position of said motor at said transmitting station to withdraw said follower at least during the initiation of said change.

9. The combination of claim 8, in which a similar cam and follower are provided at the transmitting station, said last mentioned cam being fixed to rotate with the self-synchronous motor at said transmitting station and means responsive to said change in position of said,

motor at saidtransmitting station to also withincrease in current in the self-synchronous circuit.

11. In an engine room telegraph system, a deck indicator and an engine room indicator, each comprising a motion transmitting device having a dial and a pointer and a motion receiving device having a dial and a pointer, means interconnecting the transmitting device of each indicator with the receiving device of the other indicator for synchronous operation, an alarm bell at the deck indicator and an alarm bell at the engine room indicator means including a time delay means for ringing said alarm bell at said deck indicator when the transmitter and receiver at said deck indicator are in misalignment, and means including a time delay means for ringing said alarm bell at said engine room indicator when the transmitter and receiver at 16 said engine room indicator are in misalignment, the time delays inserted by said two time delay means being difierent.

HERMAN H. CURRY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,099,673 Sullivan June 9, 1914 1,135,040 Missbach Apr. 13, 1915 1,197,212 Kaminski sept. 5, 1916 1,419,708 Wood June 13, 1922 1,607,917 Rowland et al Nov. 23, 1926 2,184,355 Libman Dec. 26, 1939 2,348,158 Sprecker May 2, 1944 2,368,300 Heist Jan. 30, 1945 FOREIGN PATENTS Number Country Date 7,154 Great Britain July 28, 1910 412,326 Germany Apr. 25, 1925 

